Deep budget-cut proposals are threatening to force the transitional high school, known as CUNY Prep, to turn away hundreds of teens looking for a second chance. It might also have to fire a dozen staffers.

About 300 teens enroll annually in the program, which offers free classes to earn high-school credits or a high-school equivalency diploma, and guides dropouts through the early stages of college or a career with the help of the City University of New York.

About 65 percent of the students go on to earn their GED, according to the school.

The city’s Department of Youth and Community Development, which funds the Parkchester program, has proposed slashing $1.1 million of the school’s $2.4 million allotment. That would force CUNY Prep to stop admitting new students.

DYCD spokesman Michael Ognibene said reductions in federal funding required the agency to scale back a number of programs. CUNY Prep is funded through the federal Workforce Investment Act.

“The cuts were not tied in any way to performance,” Ognibene said.

About 45,000 city teens dropped out of high school last year, state figures show.